In PCT application no. US2014/024630 (“the '630 application”), entitled, “Systems, Devices and Methods for Translocation Control,” the entire disclosure of which is incorporated herein by reference, a general chemical approach to connecting a polyion onto the N-terminus of any protein is disclosed. In some of the disclosed embodiments thereof, one step of such a process is functionalizing the N-terminus of a protein with an alkyne moiety for subsequent ligation to any azide containing group by conventional “click” chemistry.3 In some of the disclosed embodiments of the '630 application, this step takes place at the N-terminus, without any side reactions, for example, with ε-amino group (a primary amine) of lysine. As disclosed in the '630 application, this may be achieved using 3-(2-propynyl)succinic anhydride at pH 7.6 in a sodium acetate buffer.